I watched the Dateline version of this incident. I have not read all 390 posts on the topic so apologies if this has been covered but that show left me with reasonable doubt about David's guilt. They posed the panic scenario which is plausible and would explain the damaged mask and the removed fin. I also believe oxtox may have a similar outcome. It is undetectable postmortem yet could have left the diver thrashing violently during the seizure. Since British law is based on the concept of reasonable doubt I would have to say if I were on that jury I would have been unconvinced of the prosecution's case.